This maybe off topic but it (IMO) illustrates the importance of a good teacher. Some years ago my son and I were in NYC looking at music schools and noticed that the great Cuban trumpeter Arturo Sandoval was giving a clinic at the Blue Note. So we hustled down to the Blue Note and settled in. Arturo told a story about how (recently) he had wanted to study with a famous classical trumpeter (name escapes me). So he (Arturo) invited the prospective teacher to one of his shows. Arturo said he felt pretty good about his playing and met with the teacher backstage. The prospective teacher asked him to stop by the next day for their first lesson. Arturo arrived and sat down not knowing what to expect. He said that the teacher placed in front of him a beginning trumpet book and basically had him playing whole notes for the lesson. What I find amazing is that a guy of Arturo’s skill and accomplishments still felt the need for instruction.
It was to allow Arturo to improve his embouchure. The whole notes are rhythmically and harmonically super easy to play. The only thing left to deal with is one's tone and technique. This was the lesson that Arturo's teacher was trying to convey to him. Arturo is one of the greatest virtuoso trumpet players in the world. And yet, he was willing to study something basic, to review and improve his technique via 100% musical methods. I am telling you guys, MUSIC SOLVES ALL THINGS WITHOUT FAIL.